30 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Tap any card for details
Your boiler has failed to ignite and has safely shut itself down to prevent a gas buildup.
Your boiler has failed to start up after several attempts, meaning it is currently unable to provide heating or hot water until the ignition issue is resolved.
Your boiler is failing to ignite because it cannot properly detect or initiate the spark required to start the flame.
Your boiler is struggling to keep its flame lit while in operation, which means it has safely shut itself down to prevent any issues.
Your boiler has automatically shut down because the water inside it has become dangerously hot.
Your boiler is struggling to breathe because the internal fan is not spinning fast enough to safely light the flame.
Your boiler has detected that hot water is flowing back into the unit from the wrong direction or at the wrong temperature, causing it to shut down for protection.
Your boiler is overheating rapidly because it cannot move the hot water around your radiators effectively.
Your boiler has stopped working because the water pressure inside your heating system has dropped too low.
Your boiler has stopped working because the component responsible for venting burnt gases is not communicating correctly or is failing to spin.
Your boiler has stopped working because its internal heat-sensing component is sending a faulty signal, meaning the system cannot accurately measure the water temperature.
Your boiler has stopped working because one of its internal temperature sensors is giving an incorrect reading, preventing it from safely heating your home.
Your boiler is struggling to accurately measure the temperature of your hot water, which means it has stopped providing it to prevent system errors.
Your boiler has detected a faulty reading from the flue temperature sensor, which stops the system from operating to keep you safe.
Your boiler has stopped working because it has lost the connection to the sensor that monitors the temperature of the water circulating through your heating system.
Your boiler has lost the signal from a temperature sensor that monitors the water returning to the system, causing it to stop heating as a safety precaution.
Your boiler has lost its connection to the sensor that monitors your hot water temperature.
Your boiler has stopped working because it cannot detect the temperature of the exhaust gases, which is a necessary safety check to ensure the unit is venting properly.
Your boiler has detected that the exhaust gases are becoming dangerously hot, so it has safely shut itself down to prevent damage.
Your boiler has detected that the water pressure inside your heating system is too high, which could prevent it from working safely.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Your boiler has detected that parts inside the casing have become dangerously hot, so it has safely shut itself down to prevent damage.
Your boiler has detected an internal overheating safety trigger, which has permanently shut down the system to prevent damage.
Your boiler is having a communication error because a small electronic key, which tells the system how to operate, is not being detected correctly.
Your boiler is failing to operate because the electricity supply feeding it is too low to work safely.
Your boiler has detected that the incoming electricity supply is too high, which could damage its internal electronic controls.
Your boiler is receiving an unusual signal from the solar heating sensor, which is stopping it from communicating correctly with your solar panels.
Your boiler is not receiving a signal from a solar heating sensor, likely because the wire has become loose or disconnected.
Your boiler is detecting an electrical fault with the sensor connected to your solar water heating system.
Your boiler is having trouble communicating with the optional solar water heating system, which may prevent your hot water from being heated by solar energy.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes